>>49464924>>49465121You get so many grit items that you can boost most of your team's stats to significant degrees, you get two nature mints to fix the shit natures in your team, X item equivalents, and you should have collected a fuckton of exp candies by now. Not to mention you have easy access to a move tutor as well as seeds of mastery and high-level rebattleable trainers for even more exp.
After losing once I went through all my grit items, fixed movesets and just went for it again with a team averaging at level 58. Reset once due to an X item going to waste, and after some potion spam to wear down giratina's signature move Draining Kissu'd it to death, twice. Third try's the charm.
Pokemon is an easy game, and there have definitely been harder fights in the series' post games, not to mention fucking revive spam is still a working strategy.